Spoofing is an attempt to deceive the GNSS/GPS receiver by broadcasting signals that the receiver will use instead of the live sky signals. This article describes a test system for spoofing allows testing the three major factors to consider in a spoofing attack, time synchronization to the signals to be spoofed, power level of the spoofing signal compared to the live sky signals, and accuracy of the position obtained by the spoofing signal to that of the actual position of the device being spoofed. Using a spoofing test system will allow a user to better understand the receiver and harden the system against spoofing attacks.